Library of galaxy histories reconstructed from motions of stars

Just as the sun is moving within the Milky Way, all the stars in galaxies are moving, but with very different orbits. Some of the stars have strong rotations, while others may be moving randomly with no clear rotation. Comparing the fraction of stars on different orbits, researchers can determine how galaxies form and evolve. An international team of astronomers has derived directly, for the first time, the orbital distribution of a galaxy sample containing more than 300 galaxies of the local universe. The results, published in Nature Astronomy, are based on the CALIFA survey, a project developed at Calar Alto Observatory and conceived from the Institute of Astrophysics of Andalusia (IAA-CSIC).